The availability of waterproof or water resistant fabrics for outerwear presents challenges to create seams that share the water shedding characteristics of the fabrics. Laminated waterproof fabrics typically contain an outer face fabric of water repellant material, an inner insulating fabric such as polar fleece, with a hydrostatic barrier material between the inner and outer fabrics. The use of laminated fabrics containing a hydrostatic barrier material poses the problem of how to join the barrier material across a seam without introducing leak pathways. Existing methods of joining such fabrics to form a waterproof seam are unsatisfactory and commercially non-viable because they result in a bulky, stiff, and unattractive seam; because they do not succeed in fully merging the hydrostatic barrier across the seam; or because they are difficult and time consuming to manufacture. Thus, there remains a need for improved methods and seam designs for creating waterproof seams for outer garments and other textile products.